This ordinary, generic drug has some extraordinary uses, especially when it comes to treating exposure to nerve gases.

In the hours following the reported chemical weapons attack in the suburbs of Damascus last Wednesday, ailing men, women, and children flocked to the city's hospitals. Doctors in the Syrian capital treated thousands of patients who were experiencing neurotoxic symptoms, including pinpoint pupils, foaming mouths, convulsions, blurry vision, and difficulty breathing. The symptoms point to exposure to sarin gas or another drug agent, a weapons expert told Bloomberg. To combat the effects of what might be the world's worst chemical weapons attack in 25 years, the hospital staff turned to atropine—at least until they ran out of the drug.

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"Atropine, in large quantities, is the antidote to these nerve gases," says Rahul Khare, assistant director of the department of emergency medicine at Northwestern University's Feinberg School of Medicine. So how does atropine combat the effects of a nerve gas attack?

The human nervous system has two branches: the voluntary, which governs primarily muscle movement, and the involuntary, which is called the autonomic. The autonomic nervous system is then further broken down into the sympathetic and parasympathetic systems. The sympathetic controls the "fight or flight" response, while the parasympathetic helps the body relax and digest food and is sometimes referred to as the "rest and digest" system.

Khare tells PopMech that nerve agents such as sarin disrupt the parasympathetic system by blocking the neurotransmitter acetylcholinesterase, which breaks down acetylcholine, another neurotransmitter that controls several functions within the cardiovascular, gastrointestinal, urinary, and respiratory systems. Without the acetylcholinesterase to moderate the signals, the parasympathetic system is flooded with acetylcholine, resulting in overstimulation of the nerve cells.

"By blocking this neurotransmitter, patients exhibit signs and symptoms which include constricted pupils, large amounts of salivation/bronchial and lung secretions, involuntary urination, and ultimately convulsions and death due to the inability of the respiratory muscles to work, causing asphyxiation," Khare says.

Atropine is the most common drug used to combat nerve gases. Smithsonian reports that both the Egyptians and Greeks used atropine, although it wasn't until 1901 that pure atropine was made in a lab. It alleviates the symptoms brought on by nerve gas exposure by blocking the acetylcholine receptors. That way, even though the chemical attack causes an overabundance of acetylcholine in a victim's brain, the receptors do not pick up the signals and the person's nervous system has a chance to even itself out. "The important thing is to get the atropine in as quickly as possible," Khare says. "You want to do it within 30 minutes to an hour, if possible."

There is no specific dosage of atropine used to treat the symptoms brought on by nerve gas. It simply depends on how much gas the patient was exposed to. Doctors give an initial dose and then administer more until the patient's bronchial secretions stop.

The good news is that atropine is cheap and generic. You might have experienced its effects already: It is chiefly used in ophthalmology to dilate the pupil of the eye for examination of the retina. Atropine can also dry up nasal and tear-duct secretions, and it has been used to speed up slow heartbeats, preventing cardiac arrest.

Most cities have an emergency stockpile of the medicine for chemical attacks such as the one in Damascus last week. However, the atropine available to the hospitals in Syria wasn't enough to save everyone, and some patients didn't reach the hospital soon enough. Roughly 355 people died in the attack.